The present disclosure relates to a fixing device configured to fix a toner image on a sheet and an image forming apparatus provided with the fixing device.
As one of techniques to heat a fixing belt of a fixing device, a heating technique using a flat heater is known. In a fixing device of the flat heater heating technique, a cylindrical fixing belt is put between the flat heater and a pressing roller. When the pressing roller is driven to be rotated, the fixing belt is driven by the pressing roller to be rotated. Then, a sheet on which a toner is transferred is put between the fixing belt and the pressing roller to be conveyed, and the toner is fixed on the sheet.
In the flat heater heating technique, the fixing belt is slid with respect to the flat heater. Although a lubricant is applied on an inner circumferential face of the fixing belt in order to reduce a friction to the flat heater, if the lubricant is leaked from between the fixing belt and the flat heater, the lubrication effect may be deteriorated. Then, a technique to inhibit the leakage of the lubricant from between the fixing belt and the flat heater is discussed. For example, by abrading a surface of the flat heater in a movement direction of the fixing belt, recesses are formed on the surface of the flat heater. Alternatively, grooves in an axial direction of the pressing roller or mesh-shaped grooves are formed on a sliding face of the flat heater.
However, it is difficult to inhibit the leakage of the lubricant from an end portion of an inner circumferential face of the fixing belt completely by using the above technique. When the lubricant is leaked from the end portion of the inner circumferential face of the fixing belt, the lubricant may go around an outer circumferential face of the fixing belt and be adhered on the pressing roller. Then, a grip force of the pressing roller to convey the sheet is decreased and it becomes difficult to convey the sheet.